Composite piston for internal-combustion motors



F. A. PARKHURST.

COMPOSITE PISTON FOR INTERNAL COMBUSTION MOTORS.

APPLICATION FILED JULY 24,1916- RENEWED OCT. 24,19IB.

Patented Feb. 1920.

3 SHEETS-SHEET 1- llll I 1', j 'r L w 4% Patented Feb. 3,1920.

3 SHEETSSHEET 2.

F. A. PARKHURST.

COMPOSITE PISTON FOR INTERNAL COMBUSTION MOTORS.

APPLICATION FILED JULY 24,1916. RENEWED OCT! 24,1918.

Patented Feb. 3, 1920.

3 SHEETS-SHEET 3- imp STATES PATENT OFFICE.

. 2 FREDERIG A. PARKHURST, 0F CLEVELAND, OHIO, ASSIGNOR TO THE ALUMINUMCASTINGS COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

COMPOSITE PISTON FOR INTERNAL-COMBUSTION MOTORS.

Specification of Letters Patent.

Patented Feb. 3, 1920.

Application filed .Tu1y 24, 1916,-Seria1 No. 110,845. Renewed October24, 1918. Serial No. 259,596.

To all whom it may concern: Be it known that I, Fnnonnro A. PARK- HUnsT,a citizen of the United States, residing at Cleveland, in the county ofCuyahoga and State of Ohio, have invented certain new and usefulImprovements in and Relating to Composite Pistons for Internal-Combustion Motors, of which the following is a specification.

This invention relates to pistons for use particularly in internalcombustion motors. One. of the objects of my invention is to produce asimple, light, durable and efiicient skirted, composite pistonpeculiarly adapted to meet the conditions which exist within an internalcombustion motor cylinder, including the stresses and strains imposedupon the piston, principally during the explosion stroke and by the highheat generated at this time, which heat must be efliciently andeconomicallyla) utilized in the translation of heat into mechanicalenergy and (b) that not'translated into mechanical energy properlydissipated.

A, further object of my invention is the 4 production of a light weightpiston adapted to overcome in a large measure the difiiculties known aspiston slap and oil pumping.

My present invention comprises improve ments on the invention of JosephH. Bamberg disclosed in his Letters Patent of the United States NO;1,296,589. It contem-' plates providing a. relativelylight, durablecomposite piston, utilizing-the principal advantageous characteristicsof the piston invented by Mr. Bamberg and employing a guiding section ofmaterial of greater resistivity to wear than the metallic alloys ofaluminum now commercially used in piston construction, some of which arereferred to in Mr. Bambergs said patent.

Purely for the purposes of disclosure herein 1 have selected toillustrate and describe one construction of internal combustion motor.skirted piston and a modification thereof embodying my improvements.

In the drawings, Figurel is a sideeleva tion of a piston-embodying myimprovements.

Fig. 2 is a section on the lme 22, Fig. 1.

Fig. 3 is a section onthe line 3 3, Fig. 2.

Fig. 4 is a bottom plan view. l I Fig. 5 is a section and Fig. 6 abottom plan view of a modified construction of composite pistonembodying my invention.

expand 1 is the skirt, body or guide section of I the piston, which maybe made preferably of sheet metal or any material suitable to resistwear in operation within an internal combustion motor cylinder, such forexample as a section of drawn steel tubing or steel stamping. This guidesection 1 is formed with alined diametrically opposed apertures 1, 1which preferably are concentric with the axis of the wrist pin bosses,later to be described, to permit the insertion and withdrawal of thewrist pin, as desired, in the well known manner. At its lower end themetal of the section is bent inwardly and back upon itself, as indicatedat 1, and formed with an annular inner cylindrical section 1 of reduceddiameter.

In order to lighten as much as possible the sheet metal part of thepiston, apertures 1 may be formed through the inwardly turned knownconstruction and therebelow may carry diametrically opposed, inwardlyextending, annular wrist pin bosses 3.

The section 3 at the lower end of this combined head and connector maybe secured to the lower end of the skirt 1 in any suitable manner. InFigs. 2, 3 and 4 I have shown this connection to beefl'ectedby'interna'lly screw-threading the section 3andexternallyscrew-threading the outer surface of portion 1 of-the sheetmetal section of 1 the piston. When this connection is made, if desiredthe wall 3 may be heated so as to i it considerably and the screwthreaded portions of the parts 1 and 3 may be screwed together while thepart 3 is thus --'heated so as to obtain a shrink fit on this threadedconnection.

'The part 3 may be made of any desired material having a relatively lowspecific gravity and may be formed in any suitable manner; I prefer'tomake it of an aluminum alloy cast in a permanent mold and suitabl pouredand chilled so that its structure "will be relatively fine-grained andnonporous and the eutectic will substantially surround the excesssubstance in the structure. For example, this combined head andconnector 3 may be made in accordance ,with the invention of Joseph'Bamberg as set forth and described in his said Letters Patent of theUnited States No. 1,296,589. lVhere so constructed suitablestrengthening webs or ribs 3 may be provided at the head end of thepiston, in the now well known manner.

In Fig: 5 T have illustrated another way of connecting the lower end ofthe element 3 to the inner portion at the lower end of the element 1. Inthis embodiment of my invention the upper end of the inwardly andupwardly turned portion 1 of the skirt is internally screw-threaded, asindicated at 1 and the section 3 at the lower end of the combined headand connector 3 is correspondingly externally screw-threaded. When thisconnection is made, if desired, the screwthreaded section 1 of the skirtmay be heatedso as to expand it considerably, and the screw-threadedportion of the parts 1 and 3 then may be screwed together while theportion l of the guide section is thus heated so as to obtain a shrinkfit on this threaded connection.

Should it be deemed advisable to lock the section 3 to the adjacentinner annular portion of the skirt 1, this may be accomplished after theparts are screwed together by slight distortion or mutilation of one 1or more of the screw threads, in'any well known manner, not shown.

A plurality of holes 3* are provided through the sheet metal section,preferably where the metal is bent back upon itself to -forn1 the lowerend of the piston. These holes or ducts provide oil escapes or drainpassages for lubricant or oil which may collect between the skirt 1 andthe lower end of thecombined piston head and connecting element 3.-

lit will be understood that the sleeve or skirt 1 may be constructed soas snugly to fit the lnner wall of the motor cylinder which is commonlymade of iron or steel, whereas the portion of the head 3 above it may begiven a considerable amount of clearance betweenits outer periphery andthe inner wall of the cylinder to allow for all necessary expansion ofthe head due to the high temperatures to which'it is subjected. The heatabsorbed by the head is transferred downwardly by the side walls 3 tothe lower end of the skirt 1, and much of it is dissipated by radiation,so that the skirt is kept relatively cool and may be readily lubribatedto provide and maintain the proper working relationship between it andthe inner wall of the motor cylinder with which it co-acts. The fitbetween the skirt and the inner wall of cylinder, as before indicated,may be a snug sliding fit, and preferably the area of the skirt whichco-acts with the inner wall of the motor cylinder is such as to insureaeaeas against slapping or rapping of the piston against the inner wallof the cylinder. In fact, objectionable so-called piston slap, incidentto the operation of numerous types of pistons for use in internalcombustion motors, substantially is eliminated by the use of a pistonconstructed in accordance with my invention as shown in the drawings.Furthermore, a piston embodying my improvements herein describedpractically eliminates so-called oil pumping or transter of an undueamount of oil or lubricant from the crank case to the upper end of thepiston, resulting in undesirable smoking and undue'and troublesomecarbonization, among other things.

Due to the fact that the sleeve or skirt is maintained relatively coolunder all normal working conditions, the possibilities of scoring of theinner walls of the cylinder are practically eliminated.

The upper end of the skirt 1 is separated from the head 3 by an air gap.In the drawings, purely for the purpose of illustration, this air gap isshown relatively wide. The presence of this air gap or air space betweenthe upper edge of the skirt or body section 1 and the adjacent ed e ofthe piston head, insures that the heat absorbed by the piston headprincipally will be transmitted inwardly and downwardly so that suchportions of it as does reach the skirt or body by conduction will do soat the lower end of the skirt and will not be sufiicient in amount tocause the necessary expansion of the skirt to eflect binding between theskirt'and inner wall of the cylinder or scoring. TVhile this air gap, asabove stated, has been shown relatively wide for the purpose ofillustration, it will be understood that my invention contemplates anysort of a separated relationship between the upper endof the skirt andthe adjacent head 3 because of which heat will not be transmittedeficiently or readily from said head to the skirt. It will be understoodthat this relationship might be that even of a poor mechanical fit orjoint which would be a poor conductor of heat as compared with the metalof the side walls 3 so that such heat as did pass from the head to theguide section 1 would do so principally by way of the side walls 3rather than from the head to the upper end of the skirt 1.

ltt will be understood that by making the skirt or guide part of mypiston of iron or steel ll not only secure good wearing qualities butalso a coefiicient or thermal expansion much smaller than those ofthelight weight alloys such as aluminum alloys.

Both this low coeliicient of expansion and the low workingtemperature-of the piston skirt favor the close working fit of the skirtin the engine cylinder and, at the same time, full advantage is taken ofthe light weight material of the head and connecting part to reduce theweight of the piston.

By making the headand connecting part of the piston of light weightmetal such as aluminum alloy and by forming the skirt of relatively thinsteel tubing, the weight of my improved composite plston is madecomparable with that of pistons made entirely of aluminum alloys. ihislight weight is, of course," of material advantage in reducing theweight of the reciprocating parts of the engine, and pistons of myimproved construction will be found to operate comparativelynoiselessly, smoothly and efficiently'.

Certain features of the subject-matter herein disclosed but not claimed,are claimed in my co-pending application Serial No. 110,844, filed July24, 1916.-

To those skilled in the art, many modifications of and widely difieringembodiments and applications of my invention will suggest themselves,without departing from the spirit and scope thereof. My disclosures andthe descriptions herein are purely illustrative and are not intended tobe in any sense limiting.

"What I claim is:

'1. A composite piston for an internal combustion motor comprising ahead, wrist pin bosses and an extension below said wrist pin bosses castintegrally of a metallic alloy having a relatively low specific gravityin comparison with iron, and a sheet metal guide section having an outerwall adapted to engage the inner wall of a motor cylinder and a sectionbent inwardly and upwardly from the lower end of said outer wall andsecured to said cast extension below said bosses.

2. A composite piston for an internal combustion motor comprising aliead, wrist pin bosses and an extension below said wristpin bosses castintegrally of a metallic alloy havinga relatively low specific gravityin comparlson with iron, and a sheet metal guide section having an outerwall adapted to engage the mner wall of a motor cylinder and a sectionbent inwardly and I upwardly from the lower end of said outer wall andsei cured to said extension below said bosses by a shrunk screw threadedconnection between the parts. I

3. A composite piston for an internal combustlon motor comprisingiahead, wrist pin bosses and an extension below said wrist pin bosses castintegrally of a metallic alloy having a relatively low specific gravityin comparison with iron, and a sheet metal guide section having'an outerwall adapted to engage the inner-wall of a motor cylinder and a sectionbent inwardly and upwardly from the lower end of said outer wall andsecuredto said cast extension below said bosses, the

upper edge of the outer wall of said guide section being separated fromthe adjacent Wall of the head by-a relatively small air gap.

4:. A composite piston for an internal com- 'bustion motor, comprising asheet metal guide section having an outer wall adapted snugly to fit theinner wall of a motor cylinder, the lower portion of said guide sectionbeing turned inwardly and upwardly to form an inner portion of reduceddiameter at its upper inner end, and a head, wrist pin bosses andextension below said bosses cast integrally of a metallic alloy having alower specific gravity than iron, and said extension being secured belowsaid bosses to said upper end of said inner reduced portion of saidsheet metal guide section. Y

5. A composite piston for an internal combustion motor, comprising asheet metal guide section having an outer wall adapted snuglyto fit theinner wall of a motor cylinder, the lower portion of said guide sectionbeing turned inwardly and upwardly to form an inner portion of reduceddiameter 1 at its upper inner end, and a head, wrist pin bosses andextension below said bosses cast integrally of a metallic alloy having alower specific gravity than iron, and said extension being secured belowsaid bosses by a screw threaded connection to said upper end of saidinner reduced portion of said sheetmetal guide section.

6. A composite piston for an internal combustion motor, comprising asheet metal guide section having an outer wall adapted snugly to fit theinner wall of a motor cylinder, the lower portion of said guide sectionbeing turned inwardly and upwardly to form an inner portion of reduceddimensions at its upper inner end, and a head, wristpin bosses andextension below said bosses cast integrally of a metallic alloy having a'lower specific gravity than iron, and said extension being securedbelow said bosses to said-upper inner end of sald reduced portion ofsaid sheet metal guide section, the upper edge of the outer wall of saidguide section being separated from the adjacent wall of the head by arelatively small air gap.

7. A composite piston for an internal combustion motor, comprising acylindrical 1 sheet iron guide section having its outer wall adaptedsnugly to fit the inner wall of a motor cylinder, the lower free end ofsaid guide section being bent and drawn inwardly and upwardly to form aninner reduced portion, and a head, wrist pin bosses and'extension belowsaid bossescast integrally of a metallic alloy having a lower specificgravity than iron, and said extension being secured below said bosses tothe adjacent free end of said geduced portion of said sheet metalcyliner. s 1 8. A composite piston for an internal combustion motor,comprising a head, wrist pin bosses and an extension below said wristpin bosses cast integrally of a metallic alloy having a low specificgravity and a high 00- eflicient of expansion in comparison with iron,and a guide section made of wear-resisting metal having a low coeficientof expansion in comparison with the said metallic alloy and formed withan elongated cylindrical wall adapted to slidably engage the inner wallof the motor cylinder, the guide section having its upper end separatedfrom the head part of the piston by an air space and its lower endextended inward and upward and secured to the said extension below thewrist pin bosses.

9. A composite piston for an internal combustion motor, comprising ahead, wrist pin bosses and an extension below said wrist pin neee eeebosses cast integrally of a metallic alloy having a low specific gravityand a high coeificient of expansion in comparison with iron, and a guidesection made of wear-resisting sheet metal having a low coeflicient ofexpansion in comparison with the said metallic alloy and formed with anelongated cylindrical walladapted to slidably engage the inner wall ofthe motor cylinder, the guide section having its upper end separatedfrom the head part of the piston by an air space and its lower endextended inward and upward and secured to the said extenion below thewrist pin bosses.

In testimony whereof ll afix my signature.

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